Control switch assembly having variable differential and range adjustment



July 16, 1968 w 5. PETER ET AL 3,393,282

CONTROL SWITCH ASSE MBLY HAVING VARIABLE DIFFERENTIAL AND RANGE ADJUSTMENT Filed April 28, 1967 INVENTORS Will/am 8. Pete! CAar/es 6. 605s, Jr:

WM 6. 6M

United States Patent 3,393,282 CONTROL SWITCH ASSEMBLY HAVING VARIABLE DIFFERENTIAL AND RANGE ADJUSTMENT William B. Peter and Charles G. Goss, Jr., Louisville, Ky.,

assignors to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Apr. 28, 1967, Ser. No. 634,524 6 Claims. (Cl. 200-83) ABSTRACT OF THE DISCLOSURE A control switch assembly including a carriage having opposed switch contacts thereon positioned in opposed relation to opposed contact faces on a carrier, the carriage being adjustably s'hiftable for range adjustment by adjusting the relative position of the opposed switch contacts as a unit to the opposed contact faces on the carrier with at least one of the opposed switch contacts on the carriage being adjustable relative to the other for differential adjustment.

Background of the invention The present invention relates to a control switch assembly having variable differential and range adjustment, and more particularly to a control switch assembly for controlling an electrical circuit, or the like, by means of fluid pressure throughout wide variations in differential and range pressures.

Various types of control switch assemblies are known in the art which are adjustable to permit both range and differential pressure control. For the most part, these past control switch assemblies have been complex and expensive in construction, installation, maintenance, and operation, requiring a considerable number of finely tooled parts which have been readily subject to wear.

Summary of the invention In accordance with the present invention a new, use ful, and unobvious control switch assembly is provided which lends itself to ready and economical fabrication, construction and maintenance, requiring a minimum number of machine parts and yet insuring a high degree of accuracy and sensing over a broad range of operation. Further, the control switch assembly of the present invention provides a straightforward and readily comprehensible adjusting mechanism for both differential and range control in independent fashion, the assembly being easily installable as a unit as a replacement for previously used control switch assemblies.

Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.

More particularly, the present invention provides a control switch assembly comprising: a carrier movable longitudinally in response to the application of pressure thereto, the carrier having opposite contact faces thereon; guide means disposed in longitudinal alignment with the longitudinal movement of the carrier; a unitary carriage means shiftably carried on the guide means; opposed switch contacts supported by the unitary carriage means in opposed relationship to the contact faces on the carrier; and carriage actuating means to shift the carriage on the guide means to thereby adjust the range by adjusting the relative position of the opposed. switch contacts on the carriage with respect to the opposed contact faces on the carrier. In addition, the present invention provides adjusting means cooperable with at least one of the opposed switch contacts on the carriage to adjust its position relative the other so as to thereby 3,3@3,Z8Z Patented July 16, 1968 permit adjustment of the differential. Further, the present invention provides a spring means cooperating with the unitary carriage means to insure positive engagement of the carriage actuating means with the carriage.

It is to be understood that various changes can be made in the arrangement, form, and construction of the apparatus disclosed herein without departing from the scope or spirit of the present invention.

It further is to be understood that the control switch assembly of the present invention can be used for the control of gases or air as in a furnace exhaust in the metallurgical industry, or for controlling any electrical circuit as circumstances require. It further is to be understood that the means responsive to pressure of fluid can vary widely, and that the disclosure set forth hereinafter is only representative; for example, the means responsive to pressure can be in the form of a mechanical bimetallic thermostatic mechanism or can be in the form of an electrical or voltage operating mechanism if so desired.

Referring to the drawing which discloses one advantageous embodiment of the present invention:

FIGURE 1 is a front elevational view of the novel control switch assembly;

FIGURE 2 is a side elevational view of the assembly;

FIGURE 3 is an enlarged, partially exploded, isometric view of the assembly of FIGURES l and 2; and

FIGURE 4 is an exploded, enlarged view of a portion of the actuating assembly of FIGURE 3.

As disclosed in the drawing, the control switch assembly includes a carrier 2 in the form of a rectangular loop, one wall thereof being fixed by means of screw and nut assembly 3 to pressure diaphragm 4 of pres sure responsive chamber 6, which is disclosed only in part and which, it is to be understood, can be connected to a source of fluid under pressure-for example, a fluctuating gas pressure source in a metallurgical furnace system. Accordingly, as the pressure fluctuates, diaphragm 4 of chamber 6 moves up or down and in turn causes carrier 2 to move longitudinally. Carrier 2 is provided along the wall opposite that fastened to diaphragm 4 with opposite contact faces 7 and 8.

Arranged to electrically engage the opposite contact faces 7 and 8 of carrier 2 are the spaced free ends of a pair of opposed switch contacts 9 and 11. The switch contacts 9 and 11 which can be of a suitable electrically conductive leaf spring material, such as copper, are supported in insulated fashion from one leg of a U-shaped carriage 12. Carriage 12, which can be formed from any one of a number of suitable insulating materials such as Formica, is provided with a pair of spaced through apertures 13 in the base portion thereof. A tapped, internally threaded aperture 14 is also provided in the base portion of carriage 12 intermediate spaced through apertures 13, this tapped, internally threaded aperture 14 serving to receive the threaded portion of a rod of the carriage actuating assembly 16.

Carriage 12 is shiftable longitudinally relative carrier 2 by means of carriage actuating assembly 16, the carriage 12 being guided, in its longitudinal movement through a guide assembly 17 with which the carriage actuating assembly 16 cooperates. Guide assembly 17 includes rigid support bracket 18 of U-shaped cross section having a base and a pair of spaced parallel legs extending Substantially normal therefrom. One of the legs of support bracket 18 is fastened by means of screws 19 to the outside wall of pressure responsive chamber 6. The other leg serves to support carriage actuating assembly 16 in a manner described hereinafter. Disposed between the spaced parallel legs of bracket 1? are a pair of spaced, parallel guide retaining posts in the form of screws 21. Each screw 21 is arranged to pass through guide sleeve posts 22 which passes through one of the apertures 13 of carriage member 12 with a small clearance therebetween. It is to be noted that a pair of helical springs 23 are provided, each one being arranged to surround a guide sleeve post 22 so as to cooperate between the legs of support bracket 18 and carriage member 12 to insure positive engagement of the carriage with the carriage actuating means in a manner as described hereinafter.

Referring particularly to FIGURES 3 and 4 of the drawing, it can be seen that the carriage actuating means 16 includes rod 26 having an externally threaded portion 27 and a smooth surface portion 28. An externally threaded bushing 29 is mounted by nuts 30 in an aperture in one of the legs of support bracket 18 between guide posts 22 so as to receive smooth surface portion 28 of rod 26 for rotational movement of the rod therein. Suitable lock rings 31 having set screws therein cooperate with rod 26 to restrain the rod from longitudinal movement in bushing 29, but at the same time, allowing rotational movement of the rod about its longitudinal axis so that externally threaded portion 27 of the rod engages with internally threaded aperture 14 in carriage 12, thereby permitting the carriage to be shiftably adjusted in a longitudinal fashion along guide posts 22. In this connection, it is to be noted that helical springs 23 aforedescribed as surrounding guide posts 22 serve to insure that carriage 12 is urged into positive engagement with the threads on rod 26, nothwithstanding any wear of such threads over an extended period of use. Thus, it can be seen that to move carriage 12 longitudinally, it only is necessary to rotate rod 26 in one direction or the other by a suitable handle (not shown), thus causing opposed switch contacts 9, 11 which are carried in cantilever fashion on one leg of carriage 12 to move relative to the carrier 2 so as to permit a range adjustment of the switch assembly.

To effect a differential adjustment of the control switch assembly, it is to be noted that one leg of U-shaped carriage member 12 is provided with an adjusting screw 32. Screw 32 is positioned in carriage 12 to engage with turned tab portion 33 at the free end of leaf spring contact 9 to adjust the position of leaf contact 9 relative the position of other leaf contact 11 to thereby adjust the differential.

From the foregoing arrangement, it can be readily seen that the assembly permits independent adjustment of differential and range settings without disturbing or affecting either one or the other.

The invention claimed is:

1. A control switch assembly comprising: a carrier movable longitudinally in response to the application of pressure thereto, said carrier having opposite contact faces thereon; guide means disposed in longitudinal alignment with the longitudinal movement of said carrier; a unitary carriage meas shiftably carried on said guide means; opposed switch contacts supported by said unitary carriage means in opposed relation to said contact faces on said carrier; and carriage actuating means to shift said carriage on said guide means to thereby adjust the range by adjusting the relative position of said opposed switch contacts on said carriage with respect to said opposed contact faces on said carrier.

2. The apparatus of claim 1, and spring means cooperating with said unitary carriage means to insure positive engagement with said carriage actuating means.

3. The apparatus of claim 1, and adjusting means supported on said carriage to be movable therewith, said adjusting means being cooperable with at least one of said opposed switch contacts to adjust its position relative the other and thereby adjust the differential.

4. The apparatus of claim 1, said guide means comprising a support bracket of U-shaped cross section including a base and a pair of legs extending substantially normal therefrom; a pair of spaced parallel guide posts mounted between said legs of said support, said unitary carriage having a pair of apertures therethrough through which said guide posts extend; said carriage actuating means comprising a rod mounted on said support bracket between said guide postsfor rotational and restrained linear movement about its longitudinal axis, said rod having an externally threaded end portion, said unitary carriage having a mating internally threaded aperture to receive the threaded end portion of said rod whereby said carriage can be shiftably adjusted on said guide posts.

5. The apparatus of claim 1, said opposed switch contacts comprising longitudinally extending leaf springs, each supported at one of its ends in cantilever fashion on said carriage so that the free end extends in opposed relation to a contact face on said carrier, at least one of said leaf springs having its free end folded to provide a skewed tab portion; and a rotatable screw adjusting member mounted on said carriage to engage with said tab portion of said free end of said leaf spring contact to adjust said leaf contact position relative the other leaf contact and thereby adjust the differential.

6. The apparatus of claim 1, said guide means comprising a support bracket of U-shaped cross section including a base and a pair of legs extending substantially normal therefrom; a pair of spaced parallel guide posts mounted between said legs of said support, said unitary carriage having a pair of apertures therethrough through which said guide posts extend; said carriage actuating means comprising a rod having an externally threaded end portion and a smooth surface portion; a bushing mounted in one of the legs of said support brackets between said guide posts to receive said smooth surface portion of said rod for rotational movement therein; lock members cooperating with said rod member to restrain said rod member from linear movement in said bushing; said unitary carriage having a mating internally threaded aperture to receive the threaded end portion of said rod whereby said carriage can be shiftably adjusted on said guide posts; a pair of helical springs surrounding said guide posts and cooperable between a leg of said support bracket and said unitary carriage means to insure positive engagement of said carriage actuating means; said opposed switch contacts comprising longitudinally extending leaf springs, each supported at one of its ends in cantilever fashion on said carriage so that the free end extends in opposed relation to a contact face on said carrier, at least one of said leaf springs having its free end folded to provide a turned tab portion; and a rotatable screw adusting member mounted on said carriage to engage with said turned tab portion of said free end of said leaf spring contact to adjust said leaf contact position relative the other leaf con tact and thereby adjust the differential.

References Cited UNITED STATES PATENTS 1,246,625 1l/l9l7 Lundell 200-l66 2,500,457 3/1950 Hess 200-83.91

2,800,549 7/1957 Guthrie ZOO-83.91

2,934,618 4/1960 Beller et al 200-83.91

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Exrmlilzer. 

